I have discovered that when we choose to connect spark with rc to 2.4 the controller with the phone reconnect in 5,8 .Maybe the fault is in the controller not in spark firmware...

This was discussed several times, it is a bug. You can change it to 2.4 with OTG, see this topic. http://forum.dji.com/thread-104427-1-1.html

No you did not understand....I installed network analyzer pro to see if any Wi-Fi problems. Forget OTG .In first aircraft says it is in 5,8ghz with the remote I saw that the remote was connected with my phone in 2,4ghz .So I changed the aircraft to 2.4 ghz it goes 2,4ghz OK and the phone says that it connects with remote in 5,8ghz!!!!As  I can understand when ac is connected to rc in 5,8 ghz,  the controller connects with smartphone in 2,4ghz.On the other side when at is connected with the rc in 2,4ghz the connection between the rc and smartphone is in 5,8 ghz!!!!!

vasi Posted at 2017-8-23 07:28
This was discussed several times, it is a bug. You can change it to 2.4 with OTG, see this topic. http://forum.dji.com/thread-104427-1-1.html

This is not a good way of connection....Connection must me 2.4 ghz always with rc to phone and if you want 5.8 ghz connection with rc to ac and if you want 2.4 ghz connection , ac with rc in 2.4 in different channel ( the most stable ) in order not to create any problems with the rc to phone connection

Anuvis Posted at 2017-8-23 08:39
This is not a good way of connection....Connection must me 2.4 ghz always with rc to phone and if you want 5.8 ghz connection with rc to ac and if you want 2.4 ghz connection , ac with rc in 2.4 in different channel ( the most stable ) in order not to create any problems with the rc to phone connection

Sorry mate, I really lost it now, do not understand a word from what you want to say.
I do not care about the connection between the RC and phone as I use OTG.
Anyway, it is just the video feed between the RC and phone and I do not understand why do you care about this frequency.
I am curious now to see if someone understands your point and able to provide answer on it as well.

Anuvis Posted at 2017-8-23 08:39
This is not a good way of connection....Connection must me 2.4 ghz always with rc to phone and if you want 5.8 ghz connection with rc to ac and if you want 2.4 ghz connection , ac with rc in 2.4 in different channel ( the most stable ) in order not to create any problems with the rc to phone connection

I'm not sure to follow you either...

Did you analysed WiFi channels that are "in air" from the same phone used to do the connections or from an external device ?

This week end I'll go to a no WiFi place (I've got some yeah !) and will try thsi kind of test.

My concern (explained in this thread : http://forum.dji.com/thread-110106-1-1.html) is that when in OTG, the app display "5.8GHz" but the range i'm getting are much clother to the ones I should get in 2.4GHz so this may mean that the displayed frequency is not accurate and somehow rejoin what you tryied to explain (with the big difference that I'm using OTG so the display would only be for RC to AC)

Guys its is simple.Open ac open rc open phone NOT USE OTG.Ac says its is connected with rc in 5.8 ghz in dji app.Wifi analyzer and android wifi info says that the phone is connected in the spark rc in 2.4 ghz.Now if you go to dji ap and change to 2.4 ghz connection , ac connects with the rc in 2.4 ghz BUT THE CONTROLLER CHANGES THE CONNECTION WITH THE PHONE IN 5.8 GHZ.Wifi analyzer and android wifi info says that he phone is connected in spark rc wifi in 5.8 GHz!!!
THE CONNECTION SHOULD BE: RC TO PHONE ALWAYS IN 2.4 GHZ ( 5.8 GHZ IF YOU WANT TO RC ) AND IF YOU WANT TO CONNECT IN 2.4 WITH THE DRONE THE CONNECTION SHOULD BE RC TO AC IN 2.4 GHZ BUT IN DIFFERENT  CHANEL THAN THE 2.4 GHZ WHICH IS THE CONNECTION BETWEEN RC TO PHONE

If I understand correctly and if what you say is true, you mean that (I'm trying to say it with my words) :

when AC and RC are in 5.8, then RC and phone are in 2.4
when AC and RC are in 2.4 then RC and phone are in 5.8

is that what you are saying for the factual part ?

if this is the case, that mean that the RC as router is able to support "dual band" simultaneous clients (as my home router can).
My first reaction is that if this is the case, it's a design choice that prevents interferences from phone - RC link to RC - AC link, and also prevent bandwdith sharing in same band channels. I would not complain too much about this.

It also means that you NEED a dual band phone if you want to fly without OTG (which is probably why I've never been able to do so with my older phone I had in beginning which was 2.4 GHz only)

edit :
It also mean that you should be able to choose channels for both the AC to RC part AND the RC to phone part in their respective bands... or one of the 2 will always be "auto"

Yes that exactly

In my opinion I believe that this is not the best way to connect.... Because you need a Rc ( router)  with significant much power than the spark controller can produce...This automatically can change to ban in CE country's  and that explains why in fcc country's there is no problem ( because the controller output is in higher db)  

Maybe I am too confused, but I think that you misunderstand the concept!
If both radio connections would be in the same band, you would be able to create your own interferences.
Or had to use Channel 1 and 11 (p.ex.) in 2.4GHz, to stay away.
It is a either or for keepin the performance as high, as possible.
In my eyes.

And yes, you need a dualband smartphone, to use it in 2.4 GHz mode.

I am sure, a couple of "there is no RC wifi after changing to 2.4 GHz" is b/c of only 2,4 Wifi receiver in phones.

That would be nice if DJI mods / other users could confirm that. I'll not be able to test myself before week-end.

As far as you can see, is the band and channel selection in App for AC to RC or for RC to phone ? What if using phone + AC only ?

I think you may be right as we have only 1 channel choice (I mean choice for one link only) in App right now and that would be totally illogical to use the same channel for 2 client devices in the same band.

If this is indeed the case, that would be nice to also have a way to fix channel (and band if the RC can handle 2 clients in same band) for the other link.

Anuvis Posted at 2017-8-23 09:55
In my opinion I believe that this is not the best way to connect.... Because you need a Rc ( router)  with significant much power than the spark controller can produce...This automatically can change to ban in CE country's  and that explains why in fcc country's there is no problem ( because the controller output is in higher db)

this is actually the opposite :

the regulation gives a max total power in a given band (not per channel), but you have to share this transmit power between all channels. You are not restricted in simultaneously using max power in separated bands (like 2.4 and 5.8 wich have their own independant regulations).

if you have one device per band, then you are able to use max power in that band for each device